Swivel joints and rotary couplers for various types of apparatus are known. For example, swivel joints for connection of a pair of pipes wherein one pipe may swivel with respect to the other are shown in U.S. Pat. Nos. 1,297,370, 2,279,969 and 3,089,713 and British Pat. Nos. 762,196 and 1,435,498. Each of these patents shows the use of at least one bearing in order to allow one of the pipes to rotate with respect to the other. These patents also show some type of sealing mechanism. U.S. Pat. No. 2,279,969 utilizes a face seal, while the other patents show some type of packing mechanism or seal which expands as it is subjected to the pressure of the liquid. These patents, however, are directed to low pressure (likely below 2,000 PSI) and low speed swiveling applications. U.S. Pat. Nos. 1,297,370 and 3,089,713 use either a single ring of ball bearings or a pair of cooperating rings of ball bearings. The other three patents show pairs of bearings located nearly adjacent each other. The British patents show a spacing element separate from both the shaft and the housing. None of these devices contemplate high speed shaft or pipe rotation, nor the elimination of shaft or pipe vibration during such rotation. Furthermore, since the swivel joints are designed for low pressure applications, the bearing design is not critical to the reliability of the seal.
Various sealing and packing combinations are also known. U.S. Pat. No. 4,192,519 shows a plurality of rings used in sealing the access opening in a pressure vessel. Somewhat similarly, U.S. Pat. No. 4,262,690 shows a plurality of packing rings for sealing the stem on gate valves. Although the stem is not static as in the previous example, a valve stem rotates relatively slowly.
Additionally, in recent years there have been various attempts at designing rotary coupling mechanisms for transmitting high pressure liquid (e.g. 15,000 PSI or greater). In general, these attempts have failed because the high pressure and high rotation environment has caused seal failure within a few seconds. These attempts serve to distinguish the physical environment of low pressure and low swiveling rotation as in the patents discussed hereinbefore from an environment of high pressure and high speed rotation. High speed rotation implies radial and axial loading forces not present in static and swiveling situations which must be isolated from or absorbed by the high pressure sealing mechanism. Thus, although the prior art has addressed low pressure, low speed situations, its relevance must be questioned in view of the different challenge presented by the high pressure, high speed situation. The present invention is directed to solving this challenge.